Offset printing press



Aug. 15', I. A. HUNTING 2,356,058

OFFSET PRINTING PRESS 7 Filed Sept. 16, 1939 10 Sheets-Sheet 1 Aug. 15, 1944. A. HUNTING 2,356,058 z OFFSET PRINTING PRESS I Filed Sept. 16. 1939" 10 Sheets-Sheet 2 INVENTOR Fig. 4-

1944. a. A. HUNTING OFFSET PRINTING PRESS Filed Sept. 16, 1939 IO SheetS-Sheet 5 Jig-L INVENTOR.

Aug. 15, 1944.

I. A. HUNTING OFFSET PRINTING PRESS Filed Sept. 16, 1939 10 Sheets-Sheet 6 IN VENTOR.

Aug. 15, 1944. g. A. HUNTING 2,356,053

OFFSET PRINTING PRESS Filed se t. 16. 1959 10 Sheets-Sheet 7 8- 1944- l. A. HUNTING OFFSET PRINTING PRESS Filed Sept. 16, 1939 10 Sheets-Sheet 8 IN VENTOR.

Aug. 15, 1944. A, HUNTING 2,356,058

OFFSET PRINTING PRESS Filed Sept. 16, 1939 l0 Sheets-Sheet 9 V W A AWW I v //7 ii :i aa 245 65 i ii L1 1-h 3 k 1N VENTOR. 6 7

15, 9 I. A. HUNTING OFFSET PRINTING PRESS Filed Sept. 16, 1939 10 Sheets-Sheet l0 IN VENT OR.

Patented Aug. 15, 1944 UNITED STATES PATENT OFFICE OFFSET PRINTING PRESS Irving A. Hunting, South Plainiield, N. J.

Application September 16, 1939, Serial No. 295,197

12 Claims.

This invention relates primarily to lithographic sheet-fed offset printing presses, but some fea-- -tures may be used on other kinds of printing presses and for the feeding of sheets of paper for other operations.

The main object of this invention is to provide a press which can print a larger sheet for a given size of cylinder and run faster and more smoothly than presses now in general use.

Another object is to leave the plate and impression cylinders with fixed axes and to trip the blanket cylinder from one, and then the other,

while the gap, or the part of the cylinder not To this end I have arranged the centers of the impression and blanket cylinders in a horizontal line and the plate cylinder vertically above the blanket cylinder, and I have arranged a trip operated by a. cam attached to the impression cylinder shaft whose operating surface acts in about one quarter of the time required to turn one revolution. In this time the blanket cylinder is tripped from, or to, an adjacent cylinder, leaving the other three-quarters of the cylinder for printing.

In order to be able to trip the blanket cylinder in two directions at different times I support its bearings in stirrups swung from eccentric spindles extending through the frames below the the blanket lacks a quarter turn of starting to print on the sheet. At this time if a sheet were missed, there would not be time to set th trip and the feed roller. This gives time for detection, for setting the trip, and for tripping the blanket cylinder from the plate cylinder as the gaps pass. Then this tripping action sets the trip for tripping the blanket cylinder from the impression cylinder while the gaps are passing.

The sheet, when taken from'a pile by any suitable means, is fed forward on a smooth table at a uniform speed, about the same that it will have after being taken by the cylinder. As the sheets will not advance in exact register, they are timed to come a little too late to reach the cylinder in register, and then inthe last part of their straight travel they are pushed forward a little faster till they reach front register stops moving on a re-. ciprocating carriage at cylinderspeed. This carriage also has a side register stop, past which the sheet is fed and then pushed over against the stop before being taken by the cylinder grippers.

The carriage that carries the front and side registers is driven by a modified crank and connection at either end. These drive the carriage forward at the speed of the cylinder, while the sheet is being registered and transferred to the impression cylinder.

This carriage also supports friction elements, which, with the carriage, are lowered on to the sheet as it is being advanced at cylinder speed. These friction elements have a supplemental motion to push the sheet over the table against the register stops.

I have shown my invention in the accompanying drawings in which:

Figure 1 is a side view of a sheet-fed oflfset printing press showing the feed and the cylinders with the tripping mechanism.

Figure 2 is a section on lines AB--C-D of Figure 1 through the gears driving the feed cylinders showing the tripping mechanism.

and to trip the blanket cylinder away from the impression cylinder, nor is it the right time to trip it from the plate cylinder. Therefore I am speed and then electrically detecting the absence,

or misplacement, of an insulating sheet between two rolls placed between the impression cylinder Figure 5 is a section on line 5-5 of Figure looking in the direction of the arrows.

Figure 6 is a section on line 6-8 of Figure 4 looking in the direction of the arrows.

Figure 7 is a section on line 1-1 of Figure 4 looking in the direction of the arrows.

Figure 8 is a section on line 8-4! of Figure 4 looking in the direction of the arrows.

Figure 9 is a section on line 9-9 of Figure 8 I I looking in the direction of the arrows.

, Figure 10 is a section on line Iii-l0 of Figure 15 looking in the direction of the arrows.

arrangement for operating the feed carriage.

Figure 16 is a section on line I8--I 6 of Figure looking in the direction of the arrows.

' Figure 17 is a top view of the feed table and associated parts.

Figure 18 is a side view of the feed carriage from inside the frame with the carriage in position for the cylinder to take a sheet.

Figure 19 is a top view of the front end of the feed carriage.

Figure 20 is a section on line 2020 of Figure 19 looking in the direction of the arrows.

Figure 21 is a side view of the sheet'register.

Figure 22 is a top view of the front sheet register shown in Figure 21.

Figure 23 is a rear view of the sheet register as shown in Figures 21 and 22.

Figure 24 is a side view of one form of a friction element.

Figure 25 is a section on line 25-25 of Figure 24 looking in the direction of the arrows.

Figure 26 is an enlarged view of part of Figure 24.

Figure 27 is a side view of an alternate form of a friction element.

Figure 28 is a section on line 28-28 of Figure 2'I -looking'in the direction of the arrows.

Figure 29 is a side view of a wheel for holding a sheet against a feed tape.

Figure 30 is a top view of Figure 29.

Figure 31 is a side view of the sheet-detecting wheels and associated parts.

Figure 32 is a rear view, partly in section, of the parts shown in Figure 31.

Figure 33 is an enlarged view of an electric switch used in connection with the trip and shown I in the lower part of Figure 4.

Figure 34 is a top view of parts shown in Figure 33.

Figure 35 is a horizontal section of the register driving gear and clutch.

Figure 36 is a section on line 36-38 of Figure 35 looking in the direction of the arrows.

In these drawings each reference character designates the same part wherever shown.

The front frame 50, with a similar rear frame, supports the cylinders and other parts of a sheetfed lithographic offset printing press. The impression cylinder 5| takes and supports the sheets to be printed from a blanket 200 on the blanket cylinder 52. This receives its print from the form on a metal plate 204 held in the plate cylinder 53. The inking mechanism is shown diagrammatically as 54, and the water rollers as 55. The delivery 50 takes away the printed sheets. The sheet is taken from the cylinder grippers 51 and carried over the path 58 by grippers in a gripper bar carried by chains 59 around sprockets 60. The cylinders are shown with bearers 250 which roll to- 'gether.

, The sheets are taken from the pile 6| by the commonly-used sucker 62, or any other convenient method, and carried to the feed roller 03 under friction rolls 64. This roller is driven at cylinder speed by gear 65 and intermediate gear 06. The usual tapes 01 pass around this feed roller and over the feed table 68 which may be composed of flat bars of steel 69 resting on bars I0 extending between inside frames 1 I. These frames are carried on still shafts I2 and I3. Pulleys 10 held in brackets I5 attached to a bar I0 reach up through the table 60, receive the tapes, and return them under the table to roller 63. To keep the sheets moving at cylinder speed, small springpressed friction rolls I0 held by arms II and brackets I8 are used (see Figure 29). These may be placed where desired on rods I9. These rods ar held above the table over the sheet path by brackets 80 on rod I2. This rod also carries arms 8| for holding the friction rolls 64.

Thus the sheet is kept moving at cylinder speed till it approaches the cylinder; then the sheet is moved along the table by friction elements held on a reciprocating carriage. These friction elements rest on the sheet while the carriage is movin at cylinder speed and slide the sheet over the table to bring it to the cylinder in registered position.

This carriage 82 is reciprocated by connecting rods 03, one at either end of the carriage, operated from crank pins that have crank arms of varying length to drive the carriage at the uniform cylinder speed while the friction elements have control of the sheet.

The impression cylinder 5| has gears 84 at either end, and these, through the intermediate gears 85, 86, 8 1, and 88, drive gears 89 at cylinder speed. These gears 89 (see Figures 15, 16, and. 10) run on studs 90 and carry slides 9| in guides 9|, and these slides carry crank pins 91 to operate connecting rods 83 and reciprocate the carriage by studs 83'. The position of this slide on either end determines the length of the crank arm, and it is controlled by the fixed cam 92, in which cam roll 93 runs. This roll is carried on stud 94 extending from the slide 9| through block 95, which slides in slot 06 in gear 89. This cam is so formed that when the cam roll 93 and crank pin 91 are passing the vertical center line of gear 89, the crank arm is equal to the radius of the impression cylinder, and the crank pin 91 and the carriage 02 are moving at cylinder speed. At either side of this vertical the hubs of these levers.

line the crank arm is lengthened just fast enough to keep the carriage moving at the uniform cylinder speed, while th friction element are controlling the sheet. Then the crank arm is so controlled that the carriage is smoothly stopped, returned, and brought forward to cylinder speed again.

As to the register carriage 82, see Figures 18 and 19. This is composed of a pair of ends connected by a bar 90, the front end 99 being shown. Each end carries three wheels, I00, IOI, and I02, the first two running on top of a track I03 and the last one running under the track to hold the carriage on the track. Wheel I00 is flanged to fit the beveled upper ectges of the track I03 for guiding the carriage sidewise. These tracks are fulcrumed at the rear end on studs I04 held in the frames. The front ends of these tracks are held by a pair of levers I05 (see Figure 9) and links I06 and are guided sidewise in slots I01 in These levers are fixed to shaft H4. The height of the tracks is controlled by cam I08 and lever I09, .with roll H0, and by link III connected to lever I05. The roll is held to the cam by spring H2 and poppet H3 in the frame. Parts I08, I00, IIO, III, H2, and I I3 are not used on the rear side.

The carriage also carries a pair of shorttoothed racks II5, which, while carried forward at cylinder speed, run into mesh with the gears 04 on the impression cylinder and hold the carriage in exact register with the cylinder while the sheet is being taken by the cylinder grippers. Then the cam I08 raises the tracks till the racks clear the cylinder gears. Then the carriage is reversed and returns clear of the sheet.

On the carriage bar 93 are carried a pair of registers, the front one being shown in Figures 21, 22, and 23. The rear register is the opposite hand to this and is not shown. These are each provided with front and side register stops H5 and III and friction elements H8 and H3 for pushing the sheet against the register stops. The register stops project downward through two of a number of openings 245 in the table 63, when the carriage is down for registering a sheet. The openings used depend on the width of the sheet to be printed. Openings 246 are to clear the cylinder grippers.

The friction elements are shown here as wheels which are set to rest lightly on the sheets, and they are partly rotated to bring the sheets against the register stops. Then, still turning, they slip on the sheet till they are raised as the sheet is taken by the cylinder grippers.

To get this rotation there. is a cam I20 (see Figures18, 19, and. 20) fixed to the frame, and a lever I2I on'the carriage with a roll I22 which runs up on the cam while the friction elements are resting on a sheet to carry it against the register stops. The lever I 2I has a gear segment, I23 meshingwith a gear I24 attached by an overrunning clutch to shaft I25, which extends across the carriage through each register.

The overrunning clutch is shown in Figures 35 and 36, where I26 isa sleeve extending from the gear I24. A ratchet I2! is attached to the shaft by set screw I28 through collar I29. Each cut in the ratchet carries a small roller I30, which is slightly crowded between the sleeve and the ratchet by spring I3I. This is a fiat spring, somewhat curved, so that the ends press against a ratchet tooth and the middle, against the roller.

This clutch turns shaft I25 anti-clockwise when 5 roll I22 runs up on cam I20, but lets the shaft stand idle as spring I32 forces lever HI and roll I22 to follow down the cam till stopped against pin 241 as the carriage returns. This allows the wear on the friction element to be distributed around the wheel instead of being repeated in one spot.

Figures 24 to 28 show alternate forms of the friction elements. In the first the friction surface is composed ofiine sharp teeth formed on the metal surface of a wheel, while in'the other the friction surface is a ring of rubber or of a similar material. If the driving mechanism were changed, the friction elements might be more like .the rubber end on a lead pencil, which can illustrate the pushing of a sheet of paper over a smooth table by a friction element.

When shaft I25 is turned anti-clockwise, friction element II3 is "turnedclockwise'by gear I33 keyed to the shaft and meshing with gear I 34, which is combined with the friction element II3. In like manner, motion is conveyed to friction element, '3 through bevel gears I35 and I35 and spur gears I31 and I33. Plate I33 is clamped under bar 38 by screws from a body I'40, which carries part of the mechanism. This plate allows a clearance over the table for a sheet of paper. The friction elements extend through openings in the plate to rest on the sheet of paper, a portion of which is shown as I registered against the front and side register stops, which are fastened to plate I33.

Friction element H3 and gear I34 run on stud I42 in lever I43, which is free on shaft I25. This lever has an extension I44 which holds a hollow screw I45 for regulating the pressure of a spring I45. This is guided by a-pin I 46' extending between the screw and body I40 to give the proper pressure of the friction element on the paper. This hollow screw is held from turning by tightening down screwl. A stud I43 extends up from body I40 through I44 and carries a nut I50 to limit the swing of lever I43 when the friction element is notresting on a sheet of paper. Screw I5I can hold this nut from turning. The side register friction element II3and associated parts are like those just described. The spindle I52 running in body I 40 carries the gears I38 and I31.

It will be noted that each register is provided with a side register stop and friction element. Only one side register can be used at a time. The stop not used can be removed and the corresponding friction element lifted clear of the sheet by turning down nut I50.

Figures 22 and 23 show a guide 244 for holding the sheet from buckling between the registers. As many of them may be used as are needed.

The sheet to be printed is so fed that it can be registered against the side register stop I" close to the edge of one of the openings 245 in the table 53 as shown in Figure 23. The form is located on the plate, and the plate, on the cylin-v der to correspond closely with the sheet. Then the form is registered exactly by shifting the plate cylinder as shown in Figures 13 and 14, where 2I2 is the front end of the plate cylinder shaft. The bearings I68 are shown in these drawings as double-row preloaded ball bearings,

and each bearing is clamped to the end of the shaft. The outside of this bearing is held in sleeve 2I3 by screw cover 2I4. This sleeve is fitted into the frame free to slide but held from turning by pin 2I5. The outer end of this sleeve has screw threads cut to fit internal threads before reaching the impression cylinder; and this and then from the impression cylinder.

starts the mechanism for separating, or tripping,

the blanket cylinder, first from the plate cylinder,

This prevents overinking the blanket or printing on the impression cylinder.

The parts for this detection are shown in Figurges 1, 31, and 32, in which I53'is a still shaft extending across the press and held in two brackets I54 made from a material, such as Bakelite, that electrically insulates the shaft. Two wheels I55 of good electric conductivity run on pins I55 held in arms II'I located as desired on shaft I53. Each wheel I55 runs freely on a. wheel I55 fixed on shaft I53, running in frames II and driven bygear I50 and intermediate gears III and I52 from gear 35. Gear I54 and wheel the plate and blanket cylinders.

I56 extend up through openings in table 66, and

revolution unless insulated by an incoming sheet of paper. The leading edge of a properly fed sheet will cover this contact part and allow no electricity to pass, but if no sheet is fed, or if one or both edges lag back, an electric current of very brief duration can pass from a source of direct current I66 to shaft I53 through contact part I65 and be grounded on the press frame. .As many wheels I58 may be mounted on shaft I59 as desired, and the two wheels I55 may be placed to run on two of the wheels, I58 near the edges of the sheet being printed.

With regard to the tripping, mechanism see Figures 4 and 11. A stirrup I61 supports the bearing I68 of the blanket cylinder and hangs vertically from the overhung ends of an eccentric spindle I69, which is carried in an accentric bushing I16 in the frame and is operated by lever I82 on its outer end (see Figure 11). The stirrup has an outer part "I with a sleeve passing through the frame in an opening larger than the sleeve, and it carries the bearing I68. An inner part I12, hanging from the inner end of the spindle, supports the inner end of the sleeve. These parts may be held together by washers 25I and 252 and sleeves 253 and 254. When this spindle is turned clockwise by the attached lever I62, the bearing is lowered, and the blanket cylinder is tripped clear of the plate cylinder.

Two links I13 and I14 are carried by the ends of a similar eccentric spindle I69 (see Figure and extend horizontally to the left encircling the sleeve of the stirrup. When this spindle is turned anti-clockwise, the bearing is carried to the left, and the cylinder is tripped clear of the impression cylinder. The rear end of the blanket cylinder is supported in a similar way.

To operate these two tripping actions, the cam I15 is fastened to the end of the impression cylinder shaft. This cam has an easy lift for onequarter turn, followed by a drop for one-quarter turn, and the high point is set about 45 ahead of the gripper edge of the cylinder. Lever I16, fulcrumed on stud I11, carries a roll I11 and is held against the cam by sprin I18. The double- 'shouldered pushing connection I19 is connected to the outer end of this lever. Lever I66 carries two pins I84 and I85 and a guide plate I66 over I19. When connection I19 pushes on pin I64, it brings lever I66 and link I83 into straight toggle position (if they are not already so) with lever I82 and associated parts in printing position for When connection I19 is swung to'the right, it contacts pin I85 and swings lever I66 to the left, breaking the toggle and tripping the blanket cylinder away from the plate cylinder.

Lever I61, connection I68, pins I89 and I96, shaft I9I, and associated parts are similar to those just described. When connection I68 pushes pin I89, it brings lever I92 and link I93 into straight toggle position (if they are not already so) with the associated parts in printing position for the blanket and impression cylinders. When connection I66 is lifted, it pushes pin I96, breaking the toggle and tripping the blanket cylinder away from the impression cylinder.

It has a small surface which 7 Corresponding to levers I86 and I92 there are similar levers attached to the shafts IN and IN on the rear side of the press, but without the pins, and, as in common practice, the levers have springs and stop pins that hold them in either tripped or printing positions.

Lever I98 carries roll I65, which, pressed by spring 246, tends to follow cam I15 but may be held in high position by pawl I96 holding an arm I91 of this lev'er. In this position the cylinders run in printing contact. But if pawl I96 is lifted as an armature by the electromagnet 269 while the high point of the cam is. under roll I95 (onehalf turn from where shown), the roll will follow down the cam for one-quarter turn, and. arm I96 of lever I94 through connection I99 will swing lever 266 to the right. Then this lever, working through connection 255, will swing connection I19 against pin I85 and, during the next quarter turn of the cam, will trip the blanket cylinder from the plate cylinder. During this tripping action, lever 26I will be swung clockwise by link 262 and will lift connection 263, thus bringing connection I88 against pin I96; and the next quarter turn of cam I15 will trip the blanket cylinder away from the impression cylinder, as the gaps of these cylinders are passing.

It will be noted that, to trip the press, pawl I96 must rise one-half turn before the position shown in the drawings, and connection I19 will be set for tripping the blanket cylinder from the plate cylinder during the next quarter turn. The tripping of the blanket cylinder from the plate cylinder occurs during the following quarter turn, being finished in the position in which the cylinders are shown (that is, just as the grippers are closed).

In Figure 9 this position is shown more clearly with the grippers 51 just closed. The gap in the blanket cylinder has passed the plate cylinder and. is about to pass the impression cylinder while it is being tripped from the impression cylinder. The plate 264 is stretched on the plate cylinder by clamps 265, and the blanket 266 is held by reels 261. The gripper-operating lever 268 with roll 269 has just left the high part of cam 2I6 held to the frame by bracket 2I I.

Figure 12 shows some of the tripping parts in developed form in order to illustrate their relagize the electromagnet 249 for lifting pawl I96.

Therefore I am using an electronic control which may be supplied by an electrical production company and placed in container 22I. This will contain a rectifier to supply, fromalternating power current, direct current of low voltage which may be grounded'on the machine. This current supply will be used over line I66 in the detecter, and the brief current from this will be used to excite an electronic tube which starts another direct current from the rectifier. This current will continue till broken by other means and in turn will be used to operate a relay to supply an alternating current from the power linefor energizing the electromagnet 249. This raises pawl I96 and rent enough to energize the magnet I91 without using a relay.

The detecting contact part I65, as shown, turns three times to each sheet fed, and so would allow three brief currents during each cycle it not insulated by a sheet. To prevent this, I ground the other end of the circuit for a sufficient time i to start the trip, and then break thegrounding during the other two contacts.

The relay-operating current is also grounded on the machine. Figures 33 and 34 show thearrangement for grounding these currents only during the time required for starting the trip.

. cam. The low part of the cam is shown .by a 1 full line as at the time of the grippers taking" a sheet, but the high part of cam I and lever 222 in contact with spring 226 is shown in light lines composed of dashes as at the time for detecting and raising pawl I96. This contact grounds the currents.

The arrangement for detecting the absence of a sheet might have utilized the photoelectric cell, or the electric eye, but this also would have used an electronic control, and I prefer the arrangement shown. In either case, th electronic control is not a part of this invention.

The tripping arrangement which has been shown is fully automatic, depending on the absence or misplacement of a sheet, but there is also a manually-operated trip. In Figures 4, 6, and '7 the eccentric spindle'I69 is held in eccentric bushing I10, which has an arm 229 con-.

trolling the position of the eccentric spindle I69. The position of this arm is held by crank 229 and connection 230. The effective length of this connection is adjusted by nuts 23I bearing against poppet 232 in arm 228. This length is set to cause bearers 250 of the cylinders to roll together and give printing contact. When lever 229 is turned over anti-clockwise, it lowers arm 228 and eccentric spindle I69 and separates the blanket cylinder from the plate cylinder. The automatic trip, if used in connection with the manual trip, would separate the cylinders still more. Shaft 233 extends through both frames and has similar parts at the rear end.

Eccentric spindle I63 is held in eccentric bushing 234, which, instead of having an arm as with I10, has a gear segment 235 meshing with a gear segment on lever 236 (see Figure 5). This lever can rock on -a fixed sleeve 231 and extends downward, where it is adjusted by nuts 238.

and held in position by crank 239, which, when turned anti-clockwise, separates the blanket cylinder from the plate cylinder. Fixed sleeve 231 with washer 256 also holds the bearing in the frame. Sleeve 249 clamps the bearing on the cylinder surface speed to the impression cylinder, means for detecting the absence or misplacement of a sheet before it should have reached the impression cylinder by the passage of a brief electric current between wheels running above and below the sheet path, and means initiated by the de- "tecting means for automatically tripping the blanket cylinder from the plate cylinder, and then from the impression cylinder.

2. In a sheet-fed ofiset printing press with plate, blanket, and impression cylinders, means for feeding sheets at essentially cylinder surface speed from a sheet feeder to the impression cylinder, means located between the feeder and the impression cylinder for electrically detecting the absence of 'a sheet or an improperly fed sheet, a tripping mechanism initiated by the detecting means, for automatically tripping the blanket cylinder-from the plate cylinder and then from the impression cylinder.

3. In a sheet-fed offset printing press having a plate cylinder, a blanket cylinder, and an impression cylinder, the plate and impression cylinders having fixed axes, means for automatically tripping the blanket cylinder from and to the plate cylinder and, then, from and to the impression cylinder, in each case tripping while the gaps of the adjacent cylinders are'passing.

4. In a. sheet-fed offset printing press having a plate cylinder, a blanket cylinder, and an impression cylinder, the plate and impression cylinders having fixed axes, means for supporting the blanket cylinder by stirrups hanging from eccentric spindles between the plate and blanket cylin-e der bearings in such a way that the rocking of the spindles will trip the blanket cylinder from or to the plate cylinder, and means for holding said blanket cylinder in relation to the impression cylinder by links from eccentric spindles located between the impression and blanket cylinder hearings in such a way that the rocking of the spindles will trip the blanket cylinder from or to the impression cylinder.

5. In a-sheet-fed offset printing press having plate, blanket, and impression cylinders, a tripping mechanism including a single cam on the end of the impression cylinder shaft, with its followers arranged around the cam to be acted upon in sequence, so that it sets means for tripping the blanket cylinder from the plate cylinder, trips the blanket cylinder from the plate cylinder, and then trips the blanket cylinder from the impression cylinder.

6. In a sheet-fed ofiset printing press having plate, blanket, and impression cylinders, the plate and impression cylinders runningon fixed axes,. means for supporting the blanket cylinder from two pairs of eccentric spindles in such a way that rocking one pair of spindles will trip the blanket cylinder from the plate cylinder, and rocking the other pair of spindles will trip the blanket cylinder from the impression cylinder.

7. Ina sheet-fed offset printing press with plate, blanket, and impression cylinders, means for automatically tripping the blanket cylinder in two directions by rocking eccentric spindles, eccentric bushings located in the frames and holding the eccentric pindles, and means for manually rocking the bushings to also trip the blanket cylinder.

8. In an offset printing pres having plate, blanket, and impression cylinders, means for supporting the blanket cylinder in two directions from two sets of links in such a way that, by moving one set of links, the blanket cylinder is tripped from the plate cylinder, and then, by

moving the other set of links, initiated by the first tripping action it is tripped from the impression cylinder.

9. In an offset printing press having plate, blanket, and impression cylinders, the blanket cylinder being supported from a pair of eccentric spindles in such a way that rocking the spindles will move it from or toward the plate cylinder, and held from another pair of eccentric spindles in such a way that rocking these spindles will move it from or toward the impression cylinder.

10. In a sheet-fed ofiset printing press havin plate, blanket, and impression cylinders, means for automatically tripping the blanket cylinder from the plate cylinder during the time that the gaps of these cylinders are passing the line con-.

necting their centers; then, initiated by this tripping action, means for automatically tripping the blanket cylinder from the impression cylinder while the gaps of these cylinders are passing the line connecting their centers.

V 11. In a sheet-fed ofiset printing press having plate, blanket, and impression cylinders, means for electrically detecting the absence or misplacement of a sheet before it should have reached the impression cylinder, and means, initiated by the detection, for automatically tripping the blanket cylinder from the plate cylinder and then initiated by this tripping action, means for tripping it from the impression cylinder.

12. In a printing press having plate, blanket, and impression cylinders, means for tripping the blanket cylinder out of cooperation with the plate and impression cylinders, including movable bearings for the blanket cylinder, first supporting members for each of the cylinder bearings, pivotally supported to swing the member toward and from the impression cylinder, second supporting members for each of the cylinder bearings, pivotally supported to swing the members toward and from the plate cylinder, and eccentrically formed pivots for the pivotally supported members, adapted to move the bearings and thu to move the cylinder into and out of cooperation with the plate and impression cylinders when the pivots are rocked.

IRVING A. HUNTING. 

